Recent years have seen a considerable upsurge in the use of so-called "gasohols" as fuel in spark ignition engines. It is generally considered that the introduction of such fuels occurred as a result of the so-called "energy crisis" in an attempt to find alternatives to pure petroleum fuel. By incorporating moderate percentages of alcohol in a fuel blend, a lesser requirement for gasoline resulted.
At least initially, ethanol was the most frequently used alcohol in such blends. However, because ethanol was more expensive than gasoline on a gallon for gallon basis, such blends were not widely received by the purchasing public unless the price of the blend was subsidized. As a consequence, the initial fervor with which such blends were received soon diminished.
In the same time period, legislation has been enacted mandating the use of unleaded fuels in more recently manufactured vehicles. The removal of lead from fuels for such vehicles lowered the octane rating of such fuel and a frequent complaint was that the use of unleaded fuels in the engines of such vehicles resulted in pre-ignition or knock. This in turn caused many purchasers to purchase premium unleaded fuels having a higher octane so as to avoid the consequences of pre-ignition. In the marketing structure, such premium unleaded fuels could easily be sold at a price higher than the unleaded regular fuels.
It has been recognized that the addition of alcohol to gasoline acts to increase the octane of the resulting blend. As a consequence, many so-called regular or premium unleaded fuels are now made with moderate amounts of alcohol. Where such fuels are sold as a premium grade fuel, and can therefore fetch a higher price on the market, the price disadvantage previously associated with ethanol containing blends was at least partially offset. Similarly where such fuels are sold as a regular grade, a lower octane and less expensive gasoline base may be utilized to offset the price disadvantage. Moreover, in the case of methanol, the same is, on a gallon for gallon basis, less expensive than gasoline with the consequence that unleaded blends employing methanol are made at extremely competitive prices.
Thus, in many locales today there are available as fuels, gasoline blends, containing methanol or ethanol wherein the alcohol (including other alcohols such as terryl butyl alcohol) typically is present to the extent of about 10%. Such blends can and are used interchangeably with pure gasoline as fuel in spark ignition engines without any substantial modification to the engine to accommodate the use of alcohol because of the presence of alcohol in only a moderate percentage.
However, at much higher alcohol percentages, such spark ignition engines will not run properly without major modification. This fact poses no difficulty in the use of blends as mentioned above so long as they are properly mixed.
A problem can arise, however, due to a phenomena known as "phase separation" that may occur in such blends. Phase separation occurs when water is present to a minor, but nonetheless significant degree in the fuel. Such water may be introduced into the fuel by condensation of humid air over the body of liquid constituting the blend in a storage tank, seepage of ground water into a storage tank, etc. When such phase separation occurs, stratification of the fuel blend within a storage tank takes place. In the case of gasoline blends containing methanol, the lowest layer will constitute methanol and water. The uppermost layer will be substantially pure gasoline while the intermediate layer will be the gasoline and methanol blend.
Where phase separation occurs in gasoline blends containing ethanol, a lower layer of ethanol and water will be formed along with an upper layer of gasoline.
In a typical gasoline storage system, as at a filling station, the inlet for the fuel pick-up tube will be near the lowermost reaches of the storage tank. Consequently, such inlet will typically be in an alcohol and water layer when phase separation has occurred. Consequently, fuel dispensed into a vehicle or the like from such tank will not be the desired alcohol-gasoline blend, but rather, will be an alcohol and water mixture. While the water may be present in sufficiently small amounts as to not, by itself, upset proper operation of the engine which is to be fueled, such engine will not operate properly when fueled with such mixture because of the high alcohol content thereof.
While means are available to detect phase separation, some difficulty may be experienced at a typical service station in employing such means due to the relatively unskilled help there employed. The problem is further complicated by the fact that a typical employee at such service station may be unaware of whether the blend in a given tank is a methanol-gasoline blend or an ethanol-gasoline blend. Consequently, means by which phase separation in an ethanol-gasoline may be detected may not suffice to indicate phase separation in a methanol-gasoline blend, and vice versa, such that unskilled labor can determine when phase separation has occurred.
The present invention is directed to overcoming one or more of the above problems.